An in vitro model is being established to assess biochemical and molecular biological effects of dietary fiber on two colonic cell lines, LS174 and CCD841. Although fiber is defined as a non-starch polysaccharide that cannot be digested by man, there is a considerable amount of degradation of fiber that occurs in the gut as a result of bacterial action. The complex carbohydrates that may be released as a result of bacterial action may elicit a significant biological response in colonic mucosal cells. In order to study this aspect various fibers will be incubated with human fecal inoculum under anaerobic conditions. Complex carbohydrates produced by this fermentation will be isolated and characterized. The effect of these complex carbohydrates on the colonic cell lines will be monitored by assaying for 1) mucin production, 2) PGE2 synthesis, 3) Ornithine decarboxylase activity, and 4) expression of C-myc.